The compound cyclosporine (cyclosporin A) has found wide use since its introduction in the fields of organ transplantation and immunomodulation, and has brought about a significant increase in the success rate for transplantation procedures. Recently, several classes of macrocyclic compounds having potent immunomodulatory activity have been discovered. Okuhara et al., in European Patent Application No. 184,162, published Jun. 11, 1986, disclose a number of macrocyclic compounds isolated from the genus Streptomyces, including the immunosuppressant FK-506, a 23-membered macrocyclic lactone, which was isolated from a strain of S. tsukubaensis.
Other related natural products, such as FR-900520 and FR-900523, which differ from FK-506 in their alkyl substituent at C-21, have been isolated from S. hygroscopicus yakushimnaensis. Another analog, FR-900525, produced by S. tsukubaensis, differs from FK-506 in the replacement of a pipecolic acid moiety with a proline group. Unsatisfactory side-effects associated with cyclosporine and FK-506 such as nephrotoxicity, have led to a continued search for imnmunosuppressant compounds having improved efficacy and safety, including an immunosupressive agent which is effective topically, but ineffective systemically (U.S. Pat. No. 5,457,111).
Rapamycin is a macrocyclic triene antibiotic produced by Streptomyces hygroscopicus, which was found to have antifungal activity, particularly against Candida albicans, both in vitro and in vivo (C. Vezina et al., J. Antibiot. 1975, 28, 721; S. N. Sehgal et al., J. Antibiot. 1975, 28, 727; H. A. Baker et al., J. Antibiot. 1978, 31, 539; U.S. Pat. No. 3,929,992; and U.S. Pat. No. 3,993,749). ##STR2##